Glossary

Fertility treatment comes with a lot of jargon. Here's what it all means, in plain English.

A

AMH (Anti-Müllerian Hormone): A blood test that gives an indication of your ovarian reserve (how many eggs you have left). A higher level generally suggests a larger remaining egg supply. It doesn't tell you about egg quality.
Antral follicle count (AFC): An ultrasound scan that counts the small follicles visible on your ovaries at the start of a cycle. Along with AMH, it helps your clinic assess your ovarian reserve and plan your stimulation dose.
Assisted reproduction: An umbrella term for any medical treatment that helps someone conceive. Includes IUI, IVF, ICSI, and donor-assisted treatments.

B

Blastocyst: An embryo that has developed for 5 to 6 days after fertilisation. At this stage it has around 100 cells and is ready to implant in the womb. Many clinics prefer to transfer embryos at blastocyst stage because it can improve success rates.
BMI (Body Mass Index): A number calculated from your height and weight. Most ICBs set BMI limits for funded fertility treatment, typically requiring a BMI between 19 and 30, though this varies by area.

C

CCG (Clinical Commissioning Group): The predecessor organisations to ICBs. CCGs were replaced by Integrated Care Boards in July 2022, but you might still see references to them in older documents.
Commissioning policy: The document an ICB publishes setting out what fertility treatments they'll fund, and the eligibility criteria patients must meet. This is the source of the 'postcode lottery' variation.
Cryopreservation (freezing): Freezing eggs, sperm, or embryos for future use. Frozen embryos from a funded IVF cycle can sometimes be used in a later frozen embryo transfer without counting as a new 'full cycle'.

D

Donor insemination (DI): Using donated sperm to achieve pregnancy, either through IUI or IVF. Availability of NHS funding for donor treatments varies significantly by area.

E

Egg collection: A short procedure during IVF where eggs are collected from your ovaries using a fine needle guided by ultrasound. It's done under sedation and usually takes 15 to 30 minutes. Sometimes called egg retrieval.
Egg sharing: An arrangement where you donate some of your eggs to another patient in exchange for free or reduced-cost IVF treatment. Not all clinics offer this.
Embryo transfer: The stage of IVF where one or more embryos are placed into the womb. Single embryo transfer is now standard practice in the UK to reduce the risk of multiple pregnancy.
EMMA and ALICE: Two tests that analyse the bacteria in your womb lining. EMMA checks whether you have the right balance of helpful bacteria for implantation. ALICE looks specifically for bacteria that cause chronic infection of the womb lining. Often offered together, usually as a private add-on.
Endometriosis: A condition where tissue similar to the womb lining grows in other places, like the ovaries or fallopian tubes. It can affect fertility and is sometimes a factor in eligibility for funded treatment.
Endometrial scar tissue (Asherman's syndrome): Bands of scar tissue inside the womb, often caused by previous surgical procedures on the womb (such as after a miscarriage) or by infection. It can reduce the space available for an embryo to implant and may cause lighter or absent periods. Usually treated with a small camera procedure through the cervix to cut away the scar tissue.
Endometrial thickness: The measurement of your womb lining on ultrasound, checked during monitoring scans before embryo transfer. Most clinics want to see a lining of at least 7 to 8mm for transfer to go ahead, though thicker is generally better. A thin lining can sometimes be improved with medication or a longer preparation protocol.
ERA (Endometrial Receptivity Analysis): A biopsy test that checks whether your womb lining is ready for an embryo at the time of transfer. It looks at which genes are active in a tissue sample to find your personal 'window of implantation'. If yours is shifted earlier or later than average, your clinic can adjust the timing of your transfer. Usually offered privately as an add-on after failed transfers.
Euploid embryo: An embryo with the correct number of chromosomes (46 in total), identified through PGT-A testing. These embryos have a higher chance of implanting and developing into a healthy pregnancy compared to those with too many or too few chromosomes.
Expectant management: The medical term for 'keep trying naturally'. Your clinic gives you advice on timing, lifestyle, and frequency of intercourse, but no active treatment. NICE recommends this for up to 2 years for unexplained infertility before offering IVF.

F

Fertility counselling: Specialist emotional support offered before, during, and after fertility treatment. HFEA-licensed clinics are required to make counselling available to all patients. It covers the psychological impact of treatment, decisions about donors or surrogacy, and coping with outcomes. Usually free as part of your clinic's service.
Fertility MOT: An informal name for a set of initial fertility tests, usually including AMH, antral follicle count, and sometimes a semen analysis. Some private clinics offer this as a standalone package, but the same tests are available through your GP or NHS referral.
FET (Frozen Embryo Transfer): Transferring a previously frozen embryo into the womb. Some ICBs fund FET cycles from embryos created during a funded fresh cycle. It's less physically demanding than a full stimulated cycle.
Fibroids: Non-cancerous growths in or around the womb. Their impact on fertility depends on where they are. Submucosal fibroids (inside the womb cavity) are most likely to affect implantation. Intramural fibroids (within the womb wall) may distort the cavity if large. Subserosal fibroids (on the outside) and pedunculated fibroids (attached by a stalk) are less likely to cause fertility problems but may still be relevant depending on size and position.
Follicle: A small fluid-filled sac in the ovary that contains a developing egg. During IVF stimulation, the aim is to grow multiple follicles so several eggs can be collected.
FSH (Follicle Stimulating Hormone): A hormone that stimulates the ovaries to produce eggs. FSH levels are sometimes tested as part of a fertility assessment. High levels can indicate reduced ovarian reserve.
Full cycle: What counts as one funded IVF 'cycle' varies by ICB. NICE defines it as one episode of ovarian stimulation plus the transfer of any resulting fresh and frozen embryos. But some ICBs interpret this differently, so always check your local policy.

G

Genetic counselling: A specialist service that helps you understand genetic test results and what they mean for your family. Often offered before or after PGT, karyotyping, or carrier screening. A genetic counsellor explains risks, how conditions can be inherited, and your options in a way that supports your decision-making.
GP referral: The first step to accessing NHS fertility treatment. Your GP refers you to a fertility clinic after initial investigations. Some ICBs require you to have been trying to conceive for a specific period before they'll refer you.

H

Haemorrhagic cyst: An ovarian cyst that contains blood, usually formed when a blood vessel in a follicle breaks during ovulation. They're common and often resolve on their own within a few weeks. If one is spotted on a monitoring scan, your clinic may delay treatment until it clears.
Health board: The equivalent of an ICB in Scotland, Wales, and Northern Ireland. These bodies set fertility treatment policies for their region. Unlike England, the devolved nations tend to have national-level policies rather than area-by-area variation.
HFEA (Human Fertilisation and Embryology Authority): The UK regulator for fertility treatment and research. They license clinics, set standards, and publish data on clinic success rates. A good starting point when researching clinics.
HSG (Hysterosalpingogram): An X-ray test that checks whether your fallopian tubes are open. A dye is passed through the cervix and X-rays track its movement. It's part of the standard fertility workup and usually done as an outpatient.
HyCoSy and saline 3D scan: Ultrasound-based tests for checking the womb and tubes. HyCoSy (Hysterosalpingo Contrast Sonography) uses a contrast fluid to see if your fallopian tubes are open, similar to an HSG but without X-rays. A saline 3D scan (also called saline infusion sonography or SIS) fills the womb with saline to give a detailed 3D image of the cavity, useful for spotting polyps, fibroids, or scar tissue. Some clinics offer both in one appointment.
Hydrosalpinx: A fallopian tube that is blocked and filled with fluid. The fluid can leak into the womb and reduce the chances of an embryo implanting. If a hydrosalpinx is found before IVF, your clinic may recommend clipping or removing the affected tube to improve success rates.

I

ICB (Integrated Care Board): The NHS body responsible for planning and funding healthcare in your area, including fertility treatment. There are 42 ICBs in England, each with their own fertility policy. This is why funding varies by postcode.
ICSI (Intracytoplasmic Sperm Injection): A form of IVF where a single sperm is injected directly into an egg. It's used when sperm quality is poor or when standard IVF hasn't worked. Most ICBs fund ICSI when clinically indicated.
Infertility support groups: Peer support networks for people going through fertility treatment or struggling to conceive. In the UK, organisations like Fertility Network UK and local clinic-run groups offer online communities, phone lines, and in-person meetups. The HFEA website lists support options, and many clinics have their own patient groups.
IUI (Intrauterine Insemination): A simpler fertility treatment where prepared sperm is placed directly into the womb around the time of ovulation. Less invasive and less expensive than IVF, and sometimes offered as a first step.
IVF (In Vitro Fertilisation): A process where eggs are collected from the ovaries and fertilised with sperm in a laboratory. The resulting embryo is then transferred to the womb. 'In vitro' means 'in glass', referring to the lab dish.

K

Karyotype: A test that maps out all 46 of your chromosomes to check they're the right shape and in the right place. In fertility, it's usually offered to couples with recurrent miscarriage or repeated IVF failure. It can reveal if one partner is carrying chromosomes that are rearranged in a way that doesn't affect them personally but can cause problems when passed to an embryo.
KNOVA: A brand name for a type of NIPT (Non-Invasive Prenatal Testing).

L

Laparoscopy: Keyhole surgery used to look at or treat conditions inside the pelvis, such as endometriosis, fibroids, or blocked fallopian tubes. Sometimes part of the investigation before fertility treatment.

M

Microfluidic sperm selection: A technique used in the lab to separate the healthiest, most active sperm from a sample. The sperm swim through a tiny chip, and only those with good movement and less DNA damage make it through. Sometimes offered as an add-on to ICSI, particularly where sperm DNA fragmentation is a concern.
Mosaic embryo: An embryo that contains a mix of cells with the correct number of chromosomes and cells with too many or too few, identified through PGT-A testing. They sit in a grey area between fully normal (euploid) and fully abnormal. Some can still result in healthy pregnancies, and clinics may consider transferring them when no fully normal embryos are available.

N

Natural cycle IVF: An IVF cycle without stimulation drugs, where a single egg is collected during your natural menstrual cycle. Less physically intensive than standard IVF but with lower success rates per cycle. Not widely funded on the NHS.
NICE (National Institute for Health and Care Excellence): The body that produces clinical guidelines for the NHS. Their fertility guideline recommends 3 full IVF cycles for eligible women under 42. ICBs aren't required to follow this, and most don't fully.
NIPT (Non-Invasive Prenatal Testing): A blood test offered during pregnancy (from around 10 weeks) that screens for chromosomal conditions like Down's syndrome, Edwards' syndrome, and Patau's syndrome. It works by testing tiny traces of the baby's DNA found in the mother's blood. Available on the NHS as a follow-up to higher-chance screening results, or privately as a standalone test.

O

OHSS (Ovarian Hyperstimulation Syndrome): A potential side effect of the hormone drugs used in IVF, where the ovaries over-respond and swell. Mild symptoms are common (bloating, discomfort), but severe OHSS needs medical attention. Modern protocols have reduced the risk significantly.
Ovarian reserve: A general term for how many eggs you have remaining. Assessed through AMH blood tests and antral follicle counts on ultrasound. Lower reserve doesn't necessarily mean you can't conceive, but it may affect treatment options.
Ovulation induction: Using medication (usually tablets like letrozole or clomifene) to stimulate the ovaries to release eggs in people who aren't ovulating regularly. It's a less intensive treatment than IVF and is sometimes the first thing tried.
Ovulation problems: When your ovaries don't release an egg regularly, or at all. One of the most common causes of difficulty conceiving. Often linked to PCOS, thyroid issues, or premature ovarian insufficiency. Usually treatable with medication.

P

PCOS (Polycystic Ovary Syndrome): A common condition affecting how the ovaries work. It can cause irregular periods, difficulty ovulating, and is one of the leading causes of fertility problems in the UK. Treatment usually starts with ovulation induction.
PGT (Preimplantation Genetic Testing): Testing embryos for genetic conditions before transfer during IVF. PGT-A screens for chromosome abnormalities, PGT-M tests for specific inherited conditions. Not routinely funded by the NHS.
PICSI (Physiological Intracytoplasmic Sperm Injection): A variation of ICSI where sperm are selected based on their ability to bind to a substance naturally found around the egg. The idea is that more mature, higher-quality sperm are better at binding to it. Some clinics offer it as an add-on.
Postcode lottery: The variation in NHS fertility treatment access depending on where you live. Because each ICB sets its own policy, two people in identical circumstances can get different levels of funding based purely on their address.
Premature ovarian insufficiency (POI): When the ovaries stop working properly before age 40, leading to irregular or absent periods and reduced fertility. Previously called premature ovarian failure. Some ICBs have specific pathways for people with POI.
Previous children: Most ICBs restrict funded treatment to people without existing children. The exact rules vary: some count biological children only, others include stepchildren or adopted children. Some distinguish between the patient and their partner.
Previous treatment: Some ICBs won't fund IVF if you've already had cycles elsewhere, whether NHS or privately funded. The rules on what counts vary. Some only consider full IVF cycles, others include IUI or treatment abroad.

R

Recurrent miscarriage: Usually defined as three or more consecutive pregnancy losses. Some ICBs have different eligibility pathways for people with recurrent miscarriage, and it may be investigated separately from general infertility.
Referral to treatment (RTT): The NHS waiting time standard. For fertility, this is the time between your GP referral and starting treatment. There's an 18-week target, though in practice fertility waits are often longer.
Residency requirement: Most ICBs require you to have been registered with a GP in their area for a minimum period (often 12 months) before you can access funded fertility treatment. This prevents people moving postcode just to access better funding.

S

Same-sex couples: Policies for same-sex couples vary. Some ICBs require self-funded IUI attempts before offering IVF (as evidence of need), while others don't. The number of required attempts and who pays for them differs by area.
Secondary infertility: Difficulty conceiving after a previous successful pregnancy. Some ICBs don't fund treatment if you already have a child, regardless of whether you're experiencing secondary infertility.
Semen analysis: A test that checks sperm count, movement, and shape. It's one of the first investigations done and can identify male factor issues early. Usually needs to be repeated to confirm results.
Semen culture: A lab test that checks for bacterial infection in a semen sample. Infections can affect sperm quality and may cause inflammation that impacts fertility. If bacteria are found, a course of antibiotics is usually prescribed before treatment.
Single embryo transfer (SET): Transferring just one embryo at a time, which is now the recommended approach in the UK. It reduces the risk of twins or triplets, which carry higher health risks for both parent and babies.
Simple cyst: A fluid-filled sac on the ovary that's usually harmless and often disappears on its own within a cycle or two. Common and typically found incidentally on ultrasound. If one is present at the start of a treatment cycle, your clinic may wait for it to resolve before beginning stimulation.
Sperm DNA fragmentation: Damage to the DNA inside sperm cells. A man can have normal sperm count and movement but still have high fragmentation, which can affect fertilisation, embryo development, and miscarriage risk. Tested separately from a standard semen analysis. Single-stranded breaks (damage to one side of the DNA) are more easily repaired by the egg; double-stranded breaks (damage to both sides) are more severe and harder to overcome.
Stimulation (ovarian stimulation): The phase of IVF where hormone injections encourage the ovaries to produce multiple eggs instead of the usual one. Lasts around 10 to 14 days, with regular monitoring scans.
Subfertility: A term sometimes used instead of 'infertility'. Generally means difficulty conceiving after 12 months of regular unprotected sex (or 6 months if over 36). It doesn't mean you can't conceive, just that it's taking longer than expected.
Surrogacy: When another person carries a pregnancy for you. NHS funding for surrogacy-related fertility treatment is very limited and varies significantly by ICB.

T

Thrombophilia screen (thrombotic risk profile): A set of blood tests checking for inherited conditions that make your blood more likely to clot than normal. Sometimes offered after recurrent miscarriage, as certain clotting tendencies have been linked to pregnancy loss. The tests look at several natural blood-thinning proteins and clotting factors to see if any are abnormal.
Trigger injection: An injection given during IVF to trigger final egg maturation before collection. Timing is precise, usually 36 hours before the egg collection procedure.
Two-week wait (2WW): The period between embryo transfer and taking a pregnancy test. Typically around 10 to 14 days depending on the clinic. Known for being one of the most emotionally challenging parts of the process.

U

Unexplained infertility: When standard tests don't identify a clear reason for difficulty conceiving. Affects around 1 in 4 couples investigated. You're still eligible for funded treatment in most areas, usually after 2 years of trying.

W

Waiting list: The time between being accepted for funded fertility treatment and starting your first cycle. Varies by ICB and clinic, and can range from a few months to over a year depending on your area and demand.

Z

ZymOt: A brand name for a microfluidic sperm selection device.